The document discusses various chemical topics including: - Physical and chemical changes when combining hydrogen and oxygen to form water, and red and white clay to form pink clay. - The meaning of exothermic and endothermic reactions, with burning/combustion identified as an exothermic reaction. - Factors that affect the rate of a chemical reaction including concentration, temperature, and surface area. - Enzymes being described as biological catalysts that help chemical reactions occur in the body. - The law of conservation of mass as it applies to balancing chemical equations so atoms are equal on both sides.

2. Consider the following combinations and tell if
they are physical or chemical change:
Hydrogen + Oxygen Water
Red Clay + white Clay Pink Clay
Justify your answer for each combination.

3. If thermic refers to heat what do you think the
terms exothermic and endothermic mean?
Endothermic Reactions are chemical reactions
that require energy while exothermic reaction
are those that release Energy.

4. Burning or Combustion is when something
reacts with Oxygen, just as the burning of
magnesium that produced huge amount of
light. In order to happen, we need to expose
something to fire in order to burn.
Is Burning Endothermic or Exothermic
Reaction?

5. “An apple a day keeps the doctor away”..But
what if the apples appear to be brown?
What can you do about this?

6. In this game we have Vitamin C tablets and
water. Each group of students will think for 5
minutes to plan for the fastest way to react
Vitamin C with water. The groups will
compete together. The fastest group will be
the winner.

7. ● Concentration: The more the concentration
the more is the speed or rate.
● Temperature: The more the temperature
the more is the speed.
● Surface area: The more area of reactants
exposed the greater is the speed.

8. Enzymes are said to be biocatalyst. “Bio”
means it is produced by cells “ catalyst”
means helper. They help chemical reactions
take place, just as those in our body.
Let’s watch this video:
https://www.youtube.com/watch?v=XTUm-
75-PL4

9. Chemical reaction is the chemical change that
is modeled by the chemical equation. It is said
to be an equation since the number of atoms
in the reactants are equal to the number of
atoms in the products due to the Law of
Conservation Of Mass

10. The Law of the Conservation of Mass states
that "Mass is conserved in a closed system".
For chemical equations - that means that the
number of each type of atom in the reactants
is equal to the number of the same type of
atoms in the product.
atoms in reactants = atoms in products

11. A simple example goes a long way. We can form water by
combining hydrogen gas (H2) and oxygen (O2) . The
reaction looks like this:
H2 + O2 H2O
If you do some of the calculations you will find this:
2 atoms of hydrogen + 2 atoms of oxygen = 3 atom
molecule of water (there is one oxygen lost)

12. H2 + O2 H2O
Reactants Products
2 H 2H
2O not balanced 1O

13. H2+ O2 H2O
In order to balance the chemical reaction, we
have to change the coefficient (the number in
the text box) we can multiply the H2O
coefficient by 2 to balance the Oxygen.
1 1
1

14. H2 + O2 2 H2O
Reactants Products
2 H not balanced 2H 4H
2O 1O 2O

15. To Balance the Hydrogen atoms we need to
multiply the coefficient of Hydrogen in the
reactant by 2

16. 2 H2 + O2 2 H2O
Reactants Products
2 H 4H 2H 4H
2O 1O 2O
HOORAY!! It is now BALANCED...

17. Al + O2 Al2O3
C2H6 + O2 CO2 + H2O
Fe2O3 + H2SO4 Fe2(SO4)3 + H2O
CO2 + H2 CH4 + H2O
Al + CuO Al2O3 + Cu
K2O + H2O KOH
I2 + Na2S2O3 NaI + Na2S4O6
(NH4)2CO3 NH3 + CO2 + H2O